As it is known, vascular surgery together with orthopedic surgery is the one which mostly profited by the introduction of prosthetic materials.
The first substitutions of arterial trunci go back to few decades ago, when the homologous graft technique was introduced, i.e. the substitution of the injured or ill part with a similar segment taken from a corpse.
Preserved human arteries had been for many years the substitutive material of choice; however, the difficulties related to the timely finding of arterial parts of special size and shape, the need to depend on "arteries banks", and the frequent technical problems related to anastomosis caused a gradual reduction in the field of their application when substitutive plastic materials were introduced on the market.
The ideal material for vascular prosthesis should include essentially the following features: it should not have any toxic, allergic or carcinogenic action, it should be pathologically inert, i.e. it should be well tolerated by the host organism, it should have a high degree of elasticity, a good porosity and high permeability to migrating cells. The last quality is absolutely necessary so that the host fibroblasts can penetrate the thickness of the prosthesis wall by fixing the same to the surrounding tissues. Similarly, inside the channel, the cells coming from the blood can adhere to the surface and form a layer defined as neointima.
Furthermore, it is necessary that the prosthesis material can be submitted to the various sterilization procedures without losing its properties and that it can be also easily shaped by means of scissors.
Sometimes it happens that, after a shorter or longer period of time, the prosthesis detaches in the suture thus causing the formation of a scar tissue that by collapsing due to the blood pressure causes a pseudoaneurism and causes the prosthesis end to come off the artery end to which it was associated.
In this type of pathology, a layer of expanded scar tissue forms around the prosthesis, thereby the arterial blood laminar flow becomes vortical thus causing a thrombi stratification within the scar tissue itself, which may be a risk for the patient.
Currently, the sole analysis techniques available to vascular surgeons in order to detect the prosthesis detachment in the suture are x-ray, echography, angiography, i.e. blood column detection, or more recently C.A.T. (Computerized Axial Tomography) and N.M.R. (Nuclear Magnetic Resonance).
In the case of angiography, the detection of the blood column does not always allow the pathology to be detected, by x-ray the evidence of pathology is almost impossible as the prostheses currently available on the market are not radiopaque; on the contrary, by C.A.T. or N.M.R. and by echography a section detection of the pathology is possible even if it is very difficult to detect and quantify any displacement of the prosthesis end from the artery end.